There are approximately 120,000 pharmacies in the United States alone, with a current growth rate on the order of 10% per year. In some high volume pharmacies, robots are used to fill prescriptions. In some medium and low volume pharmacies, prescriptions are counted by other methods, such as manually, using weighing or counting scales, or using semiautomated apparatus such as optical beam pour through systems.
In manual counting, a pharmacist or assistant (a dispensing agent) reviews a prescription, finds the corresponding stock bottle, pours a number of units from the stock bottle, typically onto a specially-configured tray, then counts out the prescribed number of units, decanting these into a receiver bottle and returning any remaining units to the stock bottle. The receiver bottle is labeled with appropriate information, such as the prescriber's name, the name and dosage of the prescription, usage instructions, dates, and the like. This procedure is comparatively slow, and can be cumbersome.
Weighing or counting scales can quicken dispensing while providing an accurate count. With some counting scales, a first unit or known plurality of units is placed on the scale and identified as a reference weight. Next, a generally unknown number of units are placed on the scale, and the scale computes a number of units on the scale based on the reference weight. Units may be added to and removed from the scale until the desired number is indicated by the scale. It will be understood that the same operation may be performed manually, using weight readings and calculating the desired result. While generally accurate and faster than manual processes under some circumstances, a counting scale has no inherent provision for identifying damaged units, and will typically provide an integer result by including some roundoff in the computation to adjust for slight measurement discrepancies. Such devices can have reduced performance due to sample-to-sample or batch-to-batch piece weight variations, which can cause absolute count errors.
Other counting systems, such as optical beam pour through systems, also referred to as tablet counters, employ troughs and flow regulation to direct units past an optical detector, which counts the units as they slide past. Such devices may be insensitive to such errors as sample-to-sample or batch-to-batch weight variations, and may detect some types of unit defects, ignore small fragments, or otherwise include features or properties other than fundamental unit counting. Typical pour through devices rely on manual interaction by the agent during the pour through process, and may require rerunning a count—that is, transferring the units from the destination container to an intermediate container and pouring them back through—if more than the prescribed number of units are poured through initially.
Tradeoffs in using known weight-based and optical systems can include control of contamination, management of detected unit defects such as fragments of various sizes, and calibration requirements. While weight-based systems require periodic calibration to ensure accuracy, optical systems are substantially insensitive to drift characteristic of weight transducers. This may be offset by size and cost considerations, wherein pour through optical systems demand comparatively heavy use to justify resource commitment involved.
Accordingly, there is a need in the art for a counting system for pharmacy and other applications that integrates in a self-contained apparatus a machine-vision-based unit detector with associated control and message management functions.